US4137669A - Balancing mechanism for manhole covers - Google Patents

Balancing mechanism for manhole covers Download PDF

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Publication number
US4137669A
US4137669A US05/876,082 US87608278A US4137669A US 4137669 A US4137669 A US 4137669A US 87608278 A US87608278 A US 87608278A US 4137669 A US4137669 A US 4137669A
Authority
US
United States
Prior art keywords
cover
yoke
manhole
springs
spring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US05/876,082
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English (en)
Inventor
Erwin J. Nunlist
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pfaudler Inc
Original Assignee
Sybron Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sybron Corp filed Critical Sybron Corp
Priority to US05/876,082 priority Critical patent/US4137669A/en
Priority to JP14401078A priority patent/JPS54108456A/ja
Priority to CA320,084A priority patent/CA1105756A/en
Priority to CH89879A priority patent/CH637740A5/de
Priority to GB7903319A priority patent/GB2014272B/en
Application granted granted Critical
Priority to IT47907/79A priority patent/IT1113722B/it
Publication of US4137669A publication Critical patent/US4137669A/en
Priority to FR7903135A priority patent/FR2416997A1/fr
Priority to MX176529A priority patent/MX150033A/es
Priority to DE19792904608 priority patent/DE2904608A1/de
Assigned to PFAUDLER CO. INC., THE A NEW YORK CORP. reassignment PFAUDLER CO. INC., THE A NEW YORK CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: SYBRON CORPORATION A NY CORP.
Assigned to CONTINENTAL ILLINOIS NATIONAL BANK AND TRUST COMPANY OF CHICAGO, 231 SOUTH LA SALLE ST. CHICAGO, IL 60697 reassignment CONTINENTAL ILLINOIS NATIONAL BANK AND TRUST COMPANY OF CHICAGO, 231 SOUTH LA SALLE ST. CHICAGO, IL 60697 SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: PFAUDLER COMPANIES, INC., THE
Assigned to PFAUDLER COMPANIES, INC., A CORP. OF DE reassignment PFAUDLER COMPANIES, INC., A CORP. OF DE ASSIGNS THE ENTIRE INTEREST, EFFECTIVE MARCH 13, 1987 Assignors: KENNECOTT MINING CORPORATION
Assigned to NATIONAL CITY BANK, COLUMBUS, BANK ONE, DAYTON, NA reassignment NATIONAL CITY BANK, COLUMBUS SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: PFAUDLER (UNITED STATES), INC.
Assigned to PFAUDLER (UNITED STATES), INC. reassignment PFAUDLER (UNITED STATES), INC. MERGER (SEE DOCUMENT FOR DETAILS.) Assignors: PFAUDLER COMPANIES, INC., THE
Assigned to PFAUDLER COMPANIES, INC., THE reassignment PFAUDLER COMPANIES, INC., THE RELEASE BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: CONTINENTAL ILLINOIS NATIONAL BANK AND TRUST COMPANY OF CHICAGO
Assigned to PFAUDLER, INC. reassignment PFAUDLER, INC. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: PFAUDLER (UNITED STATES), INC.
Assigned to BANK ONE, DAYTON, NA reassignment BANK ONE, DAYTON, NA SECURITY AGREEMENT Assignors: PFAUDLER (UNITED STATES), INC.
Assigned to PFAUDLER, INC. reassignment PFAUDLER, INC. RELEASE OF SECURITY INTEREST Assignors: BANK ONE, DAYTON, N.A.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E05—LOCKS; KEYS; WINDOW OR DOOR FITTINGS; SAFES
    • E05F—DEVICES FOR MOVING WINGS INTO OPEN OR CLOSED POSITION; CHECKS FOR WINGS; WING FITTINGS NOT OTHERWISE PROVIDED FOR, CONCERNED WITH THE FUNCTIONING OF THE WING
    • E05F1/00—Closers or openers for wings, not otherwise provided for in this subclass
    • E05F1/08—Closers or openers for wings, not otherwise provided for in this subclass spring-actuated, e.g. for horizontally sliding wings
    • E05F1/10—Closers or openers for wings, not otherwise provided for in this subclass spring-actuated, e.g. for horizontally sliding wings for swinging wings, e.g. counterbalance
    • E05F1/12—Mechanisms in the shape of hinges or pivots, operated by springs
    • E05F1/1246—Mechanisms in the shape of hinges or pivots, operated by springs with a coil spring perpendicular to the pivot axis
    • E05F1/1253—Mechanisms in the shape of hinges or pivots, operated by springs with a coil spring perpendicular to the pivot axis with a compression spring
    • E05F1/1261—Mechanisms in the shape of hinges or pivots, operated by springs with a coil spring perpendicular to the pivot axis with a compression spring for counterbalancing
    • E—FIXED CONSTRUCTIONS
    • E05—LOCKS; KEYS; WINDOW OR DOOR FITTINGS; SAFES
    • E05Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES E05D AND E05F, RELATING TO CONSTRUCTION ELEMENTS, ELECTRIC CONTROL, POWER SUPPLY, POWER SIGNAL OR TRANSMISSION, USER INTERFACES, MOUNTING OR COUPLING, DETAILS, ACCESSORIES, AUXILIARY OPERATIONS NOT OTHERWISE PROVIDED FOR, APPLICATION THEREOF
    • E05Y2800/00—Details, accessories and auxiliary operations not otherwise provided for
    • E05Y2800/26—Form or shape
    • E—FIXED CONSTRUCTIONS
    • E05—LOCKS; KEYS; WINDOW OR DOOR FITTINGS; SAFES
    • E05Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES E05D AND E05F, RELATING TO CONSTRUCTION ELEMENTS, ELECTRIC CONTROL, POWER SUPPLY, POWER SIGNAL OR TRANSMISSION, USER INTERFACES, MOUNTING OR COUPLING, DETAILS, ACCESSORIES, AUXILIARY OPERATIONS NOT OTHERWISE PROVIDED FOR, APPLICATION THEREOF
    • E05Y2999/00—Subject-matter not otherwise provided for in this subclass

Definitions

  • This invention relates to a spring balance mechanism for manhole covers.
  • Most manhole covers on tanks, vessels and other processing equipment are hinged.
  • Manhole covers have often caused injury to operators and damage to the assembly by falling back on the manhole collar, particularly the ones on glass lined vessels.
  • Manhole covers on pressure vessels are usually very heavy and hard to operate, especially for women, who are being employed in considerably larger numbers in the processing and heavy industries.
  • spring balance devices for manhole covers By use of spring balance devices for manhole covers, a manhole cover can be opened and closed more easily and safely than a manhole cover without balance assistance, and the possibility of injury from falling covers is virtually eliminated.
  • the system described in the reference has a regressive or diminishing spring force curve.
  • the incremental change in the force exerted, for the corresponding incremental compression of the springs decreases as the springs are compressed.
  • the spring force curve should be progressive, not regressive, to more nearly match the force required to balance the manhole in any position.
  • almost all commercially available disc springs have a regressive spring force characteristic.
  • Hinged mounting systems such as the one shown in the reference typically include stops to limit the opening movement of the cover. If the cover is swung rapidly to the point where stops limit the movement, the shock of the sudden deceleration of the cover movement must be absorbed by the mounting system. High stresses can be created in this situation.
  • One object of this invention is to provide a spring balancing mechanism for manhole covers with a progressive spring force characteristic that more closely matches the force required to balance certain covers. This is accomplished by using at least two subsets of disc springs, with one set being stronger than the other. As the cover starts to close, the weaker set is compressed more rapidly, and the spring force characteristic increases after the weaker set is fully compressed. Thus, the overall spring force characteristic curve is progressive, despite the fact that the individual subsets of springs have regressive spring force characteristics.
  • Another object of this invention is to provide a spring balancing system that reduces the shock or sudden stresses produced when the cover is slammed against the backstops. This is accomplished by using another compressible member, preferably additional disc springs, which are compressed as the cover moves to a fully opened position defined by a set of stops.
  • Yet another object of the invention is to provide a mounting system and balancing aid for manhole covers that can be installed on existing glass lined vessels without welding, drilling or similar operations on the vessel that might damage it. This is accomplished by attaching the balancing system to a manhole protection ring of the type frequently used to protect nozzles on glass lined reactors from mechanical damage.
  • the shock adsorption system described above helps make this type of installation possible by reducing the stresses that can be imposed on the protection ring by opening the cover rapidly.
  • FIG. 1 is a partially sectioned view of balancing mechanism.
  • FIG. 2 is a side view of the mechanism.
  • FIGS. 1 and 2 illustrate an embodiment of this invention mounted on a manhole protection ring 11 attached to a nozzle 12 that defines a manhole opening in a glass lined vessel.
  • the nozzle protection ring 11 is secured to the nozzle by conventional clamps (not shown) that grip the edge of the nozzle and are bolted to the ring.
  • a gasket 13 is provided between the nozzle 12 and ring 11 to insure proper sealing, and a similar gasket 14 is provided between the ring and the manhole cover 20.
  • the manhole protection ring is preferably covered with a partially crystallized glass-ceramic coating. This type of coating provides adequate chemical resistance, while providing greater resistance to mechanical damage than most chemical resistant glass linings. Alternately, in some instances it may be desirable to make the manhole protection ring of a corrosion resistant metal such as HastelloyTM or InconelTM.
  • a hinge pin 18 extends through a bore 17 in each of the plates 15, and through slots 22 in hinge lugs 21 welded on the manhole cover 20.
  • the cover 20 pivots about hinge pin 18 as it moves from the closed position, shown in solid in FIG. 1, to the open position shown in phantom.
  • the slots 22 through the hinge lugs are elongated in the vertical direction to insure that the cover can compress the gasket 14 around the entire periphery of the cover.
  • backstop dogs 24 extend inwardly from the hinge lugs 21 on the manhole cover. These dogs 24 limit the opening movement of the cover by hitting the pivot plates 15 when the cover reaches the open position shown in the dotted outline in FIG. 2. Preferably, they limit the opening movement of the cover to approximately 15° past vertical, as shown in the Figure. This helps reduce the stresses that can be created in the mounting system by slamming the cover against the backstops, as compared with prior art systems which typically allowed the cover to swing 30° or more past vertical.
  • the manhole protection ring is made slightly thicker than normal to help adsorb these stresses. As will be seen in more detail below, this invention provides a shock absorption system that also helps reduce the stresses.
  • the balancing mechanism is connected to the manhole via a second hinge pin 26 which extends through a second set of bores 27 in the hinge lugs 21 on the cover.
  • Hinge pin 26 extends through a crosshead 28, and a threaded pull rod 29 is screwed into the crosshead 28.
  • the pull rod 29 extends through a yoke 31, mounted on pivot plates 15 by bolts 32, which allow the yoke to pivot to accomodate different positions of the pull rod.
  • Two sets of disc springs, 34, 35 are mounted on the portion of the pull rod 29 that extends through the yoke 31.
  • a washer 37 and adjusting nut 36 at the end of the pull rod are used to adjust the forces produced by the springs to match the force required to balance the cover as it closes.
  • a cylindrical cover 38, mounted on a pilot 33 on yoke 31, encloses and protects the springs 34, 35 on the end of the pull rod.
  • Each of the individual subsets of springs 34, 35 has a regressive or diminishing spring force characteristic.
  • the incremental change in the force exerted by the springs, for the corresponding incremental compression of the subset decreases as the springs are compressed.
  • the overall force characteristic for the system is progressive.
  • the springs in the subset 34 next to the yoke 31 are larger in diameter but also thicker than the springs in the subset 35 at the far end of the pull rod.
  • the spring force rate for the first set 34 is greater than the spring force rate for the second set 35 or in other words, subset 34 has a steeper spring force characteristic curve than subset 35.
  • both subsets of springs will compress, and the force produced on the cover will be a composite of the affects produced by all of the springs.
  • the spring force rate for the total system is less than the spring force rate for either subset 34 or 35 individually, and is dominated by the weaker subset 35, which makes it slightly regressive.
  • the springs in subset 35 will be completely flattened more rapidly than the springs in subset 34. From this point through the remainder of the travel of the cover, the change in the spring force curve will be directly attributable to subset 34. Thus, the slope of the characteristic curve will be steeper. As a result of this change in slope, the overall spring force characteristic curve, i.e., the spring force characteristic curve over the range encompassed by the vertical position of the cover and the closed position of the cover will be progressive.
  • the overall spring force characteristic curve for the system can be matched closely enough to the forces required to balance the cover so that the cover will remain stationary at any point between the vertical position and the closed position.
  • the frictional forces at the hinge pin 18 allow some latitude in acheiving this match. Because of these frictional forces, the curve of the forces required to balance the cover is a hysteresis curve, with the force required to raise the cover from any angular position always being somewhat higher than the force required to keep the cover from falling from the same position. Thus, the cover will stay at any given angular position if the forces produced by the springs are within this hysteresis curve.
  • two additional disc springs 40 are mounted in a stepped bore 41, at the front end of yoke 31. These springs, which are held in place by an annular retaining ring 42, serve to help absorb the sudden shock which could occur if the cover was rapidly swung open to the dotted position shown in FIG. 1, where the backstop dogs 24 on the manhole cover lugs 21 strike the mounting pivot plates 15.
  • a lock nut 43 mounted on the pull rod 29 engages the disc springs 40 just before the back stop dogs 24 strike the pivot plate 15. The force produced by compression of the springs 40 slows the cover somewhat, absorbing the shock that would otherwise be produced by the rapidly opening of the cover and reducing the stresses in the mounting system.
  • this invention produces a number of advantages over previous spring balancers for manhole covers.
  • the overall spring force curve is progressive, which more closely matches the forces required to balance most covers.
  • the system reduces the shock or sudden stresses that can be generated by rapid opening of the cover.
  • the balancing mechanism is mounted on the manhole protection ring, it can be installed on existing glass lined reactors without drilling welding or similar operations that might damage the lining of the vessel.

Landscapes

  • Pressure Vessels And Lids Thereof (AREA)
  • Vibration Dampers (AREA)
  • Pivots And Pivotal Connections (AREA)
  • Closures For Containers (AREA)
  • Underground Structures, Protecting, Testing And Restoring Foundations (AREA)
US05/876,082 1978-02-08 1978-02-08 Balancing mechanism for manhole covers Expired - Lifetime US4137669A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US05/876,082 US4137669A (en) 1978-02-08 1978-02-08 Balancing mechanism for manhole covers
JP14401078A JPS54108456A (en) 1978-02-08 1978-11-20 Balancer of manhole cover
CA320,084A CA1105756A (en) 1978-02-08 1979-01-23 Balancing mechanism for manhole covers
CH89879A CH637740A5 (de) 1978-02-08 1979-01-30 Ausgleichsvorrichtung fuer einen an einer tragbuegeleinrichtung angelenkten mannlochdeckel.
GB7903319A GB2014272B (en) 1978-02-08 1979-01-31 Balancing mechanism for manhole covers
IT47907/79A IT1113722B (it) 1978-02-08 1979-02-06 Meccanismo di bilanciamento per coperchi di passi d'uomo
DE19792904608 DE2904608A1 (de) 1978-02-08 1979-02-07 Entlastungsvorrichtung und befestigungssystem fuer einen angelenkten mannlochdeckel
MX176529A MX150033A (es) 1978-02-08 1979-02-07 Mejoras en dispositivo auxiliar de equilibrio para tapas de registro
FR7903135A FR2416997A1 (fr) 1978-02-08 1979-02-07 Mecanisme d'equilibrage du tampon ou couvercle pivotant d'un trou d'homme

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US05/876,082 US4137669A (en) 1978-02-08 1978-02-08 Balancing mechanism for manhole covers

Publications (1)

Publication Number Publication Date
US4137669A true US4137669A (en) 1979-02-06

Family

ID=25366967

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/876,082 Expired - Lifetime US4137669A (en) 1978-02-08 1978-02-08 Balancing mechanism for manhole covers

Country Status (9)

Country Link
US (1) US4137669A (enrdf_load_stackoverflow)
JP (1) JPS54108456A (enrdf_load_stackoverflow)
CA (1) CA1105756A (enrdf_load_stackoverflow)
CH (1) CH637740A5 (enrdf_load_stackoverflow)
DE (1) DE2904608A1 (enrdf_load_stackoverflow)
FR (1) FR2416997A1 (enrdf_load_stackoverflow)
GB (1) GB2014272B (enrdf_load_stackoverflow)
IT (1) IT1113722B (enrdf_load_stackoverflow)
MX (1) MX150033A (enrdf_load_stackoverflow)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5038520A (en) * 1990-11-01 1991-08-13 The Pfaudler Companies, Inc. Manway lift assist
GB2226361B (en) * 1988-12-23 1992-12-23 Leith Cardle & Co Ltd Telescopic spring counterbalance for hatches and like hinged covers.
US5394650A (en) * 1994-01-24 1995-03-07 Midland Manufacturing Corp. Manway cover balancing mechanism
EP0785332A1 (fr) * 1996-01-19 1997-07-23 A L M Disposif de positionnement angulaire d'une masse par rapport à un axe horizontal de support et appareil d'éclairage équipé d'un tel dispositif
US6378249B1 (en) * 1999-12-10 2002-04-30 3L Filters Ltd. Lid lifting mechanism
US6446307B2 (en) 1999-02-22 2002-09-10 Electromechanical Research Laboratories, Inc. Manway lid lifter
US20060026902A1 (en) * 2004-08-04 2006-02-09 Mckernen Timothy J Lifting mechanism for access hatch
US7127849B1 (en) 2002-09-26 2006-10-31 Gayer Jason E Manway lift device having an adjustable biasing assembly therefor
US20080196816A1 (en) * 1995-04-11 2008-08-21 Magna Donnelly Corporation Method for manufacturing an articulatable vehicular window assembly
US20080209680A1 (en) * 2005-07-27 2008-09-04 Norinco Device for articulating a Cover or Lid to a Frame in Particular of a Manhole
US7588652B2 (en) 1993-09-30 2009-09-15 Donnelly Corp. Method for making an articulatable vehicular window assembly
CN102878290A (zh) * 2011-07-15 2013-01-16 大震锅炉工业（昆山）有限公司 自平衡水平回转盖法兰人孔
EP2743210A1 (fr) * 2012-12-13 2014-06-18 Etablissements MAGYAR Procédé de fixation d'un couvercle d'orifice de citerne en matériau composite et citerne correspondante
US20140230330A1 (en) * 2011-03-09 2014-08-21 Alexandre Piermee Device to assist the opening of a covering element pivotably mounted relative to an edge of a frame
US20210396058A1 (en) * 2017-04-13 2021-12-23 Weber Knapp Company Counterbalance and method of making the same

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03111999U (enrdf_load_stackoverflow) * 1990-02-28 1991-11-15
GB2273961B (en) * 1992-12-30 1995-11-29 Gupta Sangram Sen Engine starting mechanism
DE102017106506B3 (de) * 2017-03-27 2018-03-01 ALDI SÜD Dienstleistungs-GmbH & Co. oHG Transport- und/oder Lagerbehälter
CN117002889A (zh) * 2023-09-22 2023-11-07 扬州中集通华专用车有限公司 快开式人孔盖

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1989908A (en) * 1931-10-03 1935-02-05 Hauserman Co E F Double acting pivot spring hinge
US2357044A (en) * 1941-01-31 1944-08-29 Studebaker Corp Door operating mechanism
US3615134A (en) * 1969-09-29 1971-10-26 Xerox Corp Counterbalanced and self-closing platen cover
US3665958A (en) * 1968-09-16 1972-05-30 Gpe Controls Inc Vent closure device
US3714680A (en) * 1971-11-17 1973-02-06 Weber Knapp Co Counter-balance support

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE7402411U (de) * 1974-04-18 Pfaudler-Werke Ag Mannlochdeckel-Öffnungshilfe
DE1222529B (de) * 1959-03-02 1966-08-11 Scharfenbergkupplung Gmbh Zug- und Stossvorrichtung fuer Mittelpufferkupplungen von Schienenfahrzeugen
DE1286914B (de) * 1965-04-17 1969-01-09 Kloeckner Humboldt Deutz Ag Federsatz fuer Fahrzeugachsen
FI46560C (fi) * 1971-01-13 1973-04-10 Teeri Lautasjousikonstruktio.
US3950819A (en) * 1975-01-16 1976-04-20 Weber-Knapp Company Lid counter-balance mechanism

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1989908A (en) * 1931-10-03 1935-02-05 Hauserman Co E F Double acting pivot spring hinge
US2357044A (en) * 1941-01-31 1944-08-29 Studebaker Corp Door operating mechanism
US3665958A (en) * 1968-09-16 1972-05-30 Gpe Controls Inc Vent closure device
US3615134A (en) * 1969-09-29 1971-10-26 Xerox Corp Counterbalanced and self-closing platen cover
US3714680A (en) * 1971-11-17 1973-02-06 Weber Knapp Co Counter-balance support

Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2226361B (en) * 1988-12-23 1992-12-23 Leith Cardle & Co Ltd Telescopic spring counterbalance for hatches and like hinged covers.
US5038520A (en) * 1990-11-01 1991-08-13 The Pfaudler Companies, Inc. Manway lift assist
US7588652B2 (en) 1993-09-30 2009-09-15 Donnelly Corp. Method for making an articulatable vehicular window assembly
US8235452B2 (en) 1993-09-30 2012-08-07 Magna Mirrors Of America, Inc. Window assembly for vehicle
US20090293368A1 (en) * 1993-09-30 2009-12-03 Donnelly Corporation Articulated window assembly for vehicles
US5394650A (en) * 1994-01-24 1995-03-07 Midland Manufacturing Corp. Manway cover balancing mechanism
US8668989B2 (en) 1995-04-11 2014-03-11 Magna Mirrors Of America, Inc. Vehicular sliding window assembly
US8048529B2 (en) 1995-04-11 2011-11-01 Magna Mirrors of America, Inc Vehicular rear sliding window assembly
US8322073B2 (en) 1995-04-11 2012-12-04 Magna Mirrors Of America, Inc. Vehicular rear sliding window assembly
US20080196816A1 (en) * 1995-04-11 2008-08-21 Magna Donnelly Corporation Method for manufacturing an articulatable vehicular window assembly
US7838115B2 (en) 1995-04-11 2010-11-23 Magna Mirrors Of America, Inc. Method for manufacturing an articulatable vehicular window assembly
US20110056140A1 (en) * 1995-04-11 2011-03-10 Magna Mirrors Of America, Inc. Vehicular rear sliding window assembly
EP0785332A1 (fr) * 1996-01-19 1997-07-23 A L M Disposif de positionnement angulaire d'une masse par rapport à un axe horizontal de support et appareil d'éclairage équipé d'un tel dispositif
WO1997026433A1 (fr) * 1996-01-19 1997-07-24 Alm Dispositif de positionnement angulaire d'une masse par rapport a un axe horizontal de support et appareil d'eclairage equipe d'un tel dispositif
FR2743856A1 (fr) * 1996-01-19 1997-07-25 Alm Dispositif de positionnement angulaire d'une masse par rapport a un axe horizontal de support et appareil d'eclairage equipe d'un tel dispositif
US6446307B2 (en) 1999-02-22 2002-09-10 Electromechanical Research Laboratories, Inc. Manway lid lifter
US6378249B1 (en) * 1999-12-10 2002-04-30 3L Filters Ltd. Lid lifting mechanism
US7127849B1 (en) 2002-09-26 2006-10-31 Gayer Jason E Manway lift device having an adjustable biasing assembly therefor
US20060026902A1 (en) * 2004-08-04 2006-02-09 Mckernen Timothy J Lifting mechanism for access hatch
US7908710B2 (en) * 2005-07-27 2011-03-22 Norinco Device for articulating a cover or lid to a frame in particular of a manhole
US20080209680A1 (en) * 2005-07-27 2008-09-04 Norinco Device for articulating a Cover or Lid to a Frame in Particular of a Manhole
US20140230330A1 (en) * 2011-03-09 2014-08-21 Alexandre Piermee Device to assist the opening of a covering element pivotably mounted relative to an edge of a frame
US9021743B2 (en) * 2011-03-09 2015-05-05 Ej Emea Device to assist the opening of a covering element pivotably mounted relative to an edge of a frame
CN102878290A (zh) * 2011-07-15 2013-01-16 大震锅炉工业（昆山）有限公司 自平衡水平回转盖法兰人孔
CN102878290B (zh) * 2011-07-15 2015-10-28 大震锅炉工业（昆山）有限公司 自平衡水平回转盖法兰人孔
EP2743210A1 (fr) * 2012-12-13 2014-06-18 Etablissements MAGYAR Procédé de fixation d'un couvercle d'orifice de citerne en matériau composite et citerne correspondante
FR2999544A1 (fr) * 2012-12-13 2014-06-20 Ets Magyar Procede de fixation d'un couvercle d'orifice de citerne en materiau composite et citerne correspondante
US20210396058A1 (en) * 2017-04-13 2021-12-23 Weber Knapp Company Counterbalance and method of making the same
US11702877B2 (en) * 2017-04-13 2023-07-18 Weber Knapp Company Counterbalance and method of making the same

Also Published As

Publication number Publication date
FR2416997B1 (enrdf_load_stackoverflow) 1984-04-06
DE2904608A1 (de) 1979-08-09
GB2014272B (en) 1982-05-06
JPS6233149B2 (enrdf_load_stackoverflow) 1987-07-18
DE2904608C2 (enrdf_load_stackoverflow) 1989-08-03
CA1105756A (en) 1981-07-28
GB2014272A (en) 1979-08-22
FR2416997A1 (fr) 1979-09-07
IT7947907A0 (it) 1979-02-06
IT1113722B (it) 1986-01-20
CH637740A5 (de) 1983-08-15
MX150033A (es) 1984-03-05
JPS54108456A (en) 1979-08-25

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